On Mon, 21 Apr 2008 15:44:20 -0500, Patrick O'Keefe wrote:
>
>Maybe I misunderstand what you would want REXX to do.
>
>If you're talking about some way of invoking an On-condition block,
>REXX obviously has it: you SIGNAL or CALL the block's label.
>
>If you want to verify an exec's ability to handle an abend condition
>if you haven't included an exception routine, uh, well, maybe you
>should include the routine rather than determining how to pick
>up the pieces after a failure.
>
My technique for picking up the pieces after a failure is to
improve the code so that it no longer fails. A nonzero return
code is not a failure. Reference to an uninitialized variable
is a failure.
>If you want to determine which Error/Failure/Halt/Noalue/Syntax
>conditions is raised by a particular miscoded statement you still have
>to execute the miscoded statement (or reread the doc).
>
>I think I've missed what you want.
>
Thanks. Perhaps I need to moderate some of my ancient compulsions:
I have _never_ coded a SIGNAL. Partly hangover from the 3 decades
ago "GOTO considered harmful" days; partly from needing to read
and sometimes maintain spaghetti code from programmers who branch
around their programs using SIGNAL with wild abandon, including
one who used SIGNAL for early exit from a deeply nested subroutine,
and came to me for assistance when his data set grew to the point
that the stack overflowed. (Conversely, I use, perhaps overuse
ITERATE and LEAVE to some of the same ends that they abuse SIGNAL.)
And SIGNAL mixes with CALL and DO like oil and water.
I have rarely coded an On-condition block, partly from resentment
of the technique of one of the above programmers who always codes,
roughly:
signal on syntax
...
syntax:
say 'Syntax error at line' sigl
exit 99
... thereby providing less diagnostic information than the
default Rexx traceback. But he believed that it was necessary
to code a handler for every possible exception condition.
I start every Rexx EXEC with "SIGNAL ON NOVALUE"; I never
code a NOVALUE handler. I understand that nowadays there
are instructions I can use in the handler to diagnose better
and identify which variable caused the problem. I need to
master those.
But a "SIGNAL ERROR" with no handler would provide much the
traceback and termination I desire. I'd just have to accept
no longer being able to say "I have never coded a SIGNAL."
(I also wish I could generate a Rexx traceback at some point,
but continue execution.)
Thanks,
gil
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